The first X-ray crystal structure determination of a dinuclear complex trapped in the [low spin-high spin] state: [Fe(II)2(PMAT)2](BF4)4.DMF.

The two metal centres in the doubly 1,2,4-triazole-bridged spin crossover complex [Fe(II)2(PMAT)2](BF4)4.DMF (1.DMF) are trapped in different spin states below ca. 200 K, with no evidence that this particular [LS-HS] species can be converted into the [LS-LS] form at ambient pressure.